Add nmcli to the linux installer

[ikreb7]

I want to get more independent from dbus because this is the biggest source of error. So I think we should switch tonmcli. What do you think about it?

This is only the start and I will soon add more. I want only start a discussion yet what is your opinion and what I should change or improve. You are also welcome to add stuff. I tested it only with eap-ttls-pap yet.

[twoln]

I have been meaning to go in this direction for quite a while, but did not get a free slot long enough. With nmcli it is to 100% obvious it Python is the right way to go, one could go back to what we had once - a bash script.
If you want to give it a go, then please go ahead, but I would prefer to define a separate device module so that we could keep the current one while developing the new one in parallel and having it available in test mode.

[ikreb7]

In my opinion, it is better to keep it in one file, so if nmcli doesn't work we could simple step backwards and use still dbus.

But actually I would prefer if we go backwards to a bash script. Would I get support from you if I develop a bash script? I would use the old bash file from you.

[twoln]

Since nmcli is added to the bash installer, I suggest we do not extend the Python one and close this pull request without merging.